The Eucalyptus reader for the iPhone and iPod touch would have been a hit even if Apple hadn’t made its boneheaded initial decision to bar the e-book reader due to “sexually explicit content.” Apple came to its senses, and serious readers can rejoice in that decision. Eucalyptus is really, really good. It looks and feels the way Amazon’s Kindle app should but does not.

Turn the Page: Reading an e-book on Eucalyptus is as close to that of a real book as the iPhone will allow, right down to flipping the pages instead of scrolling horizontally or vertically.

Eucalyptus by Things Made Out of Other Things is a client for Project Gutenberg’s library of nearly 30,000 titles, where readers can find such smut as the Kama Sutra of Vatsyayana and the collected works of Havelock Ellis. What sets the app apart from most of its competition is how it takes the cold, forbidding, and ugly type so typical of public-domain e-books and makes it gorgeous.

The app’s presentation and interface is reminiscent of Classics , but with a much larger selection for readers to browse and download. The experience is as close to that of a real book as the iPhone will allow. You flip pages rather than scroll vertically or horizontally. The pages resemble paper. After awhile, you almost forget you are reading on a screen.

When you launch Eucalyptus, the app will take you to the Get Books tab, where you can peruse the latest recommendations on a simple but stylish bookshelf or search for books on your own. And it is probably the best Gutenberg search engine I’ve come across. Type in a few letters and up pops potential matches. A search for “sex” produces more than two dozen books by title and subject and suggests authors with the word in their names.

The Eucalyptus interface also bears a strong resemblance to iTunes. When you find a book that interests you, tap the title and an “index card” with the title, author, Gutenberg eText number, and other information pops up. You tap Get Book and another (redundant) green button appears to download it. Eucalyptus also lets readers organize and browse easily alphabetically by author and title.

Book Mobile: Eucalyptus makes it easy to find titles, laying out recommendations on a stylish bookshelf.

Here’s what Eucalyptus does not do: It does not let you import your e-books. It does not let you import e-books from other e-book sites. It does not let you purchase e-books from online retailers such as Fictionwise. And because the app relies on the tagging embedded in the Gutenberg texts, it isn’t always possible to jump from one chapter to the next.

But one other thing Eucalyptus does impressively well let the user expand and contract the type. When I did a round-up of e-book readers , I argued that, “In a perfect world, every book would look like the volumes formatted so elegantly for Classics,” but would also have fully scalable text, with a wide variety of typefaces, text colors and backgrounds to choose from. That annoyed at least one reader, who e-mailed to say, “Making things customizable doesn't make something a good reader. The reason Classics is great for reading is because it isn’t customizable.”

The point of customization, however, is to let readers create the experience that works best for them. Eucalyptus puts the lie to correspondent’s objection. Despite some painstaking formatting, you can adjust the type size on the screen by squeezing or spreading two fingers—precisely as you would zoom in and out of a photo. Eucalyptus presents text in a way that will be easy on most eyes, but any reader put off by its relatively small default type size can fix it in a pinch.

Lastly: At $10, Eucalyptus is a pricey reader app, especially when compared to a free offering such as Stanza that also supports Gutenberg texts. Is it worth it? Are you kidding? Stanza remains the most versatile and arguably the best of the e-readers for the iPhone, but Eucalyptus represents a glimpse of the next great leap forward for iPhone e-reader apps.

Eucalyptus is compatible with any iPhone or iPod Touch running the iPhone 2.2 software update.

[Ben Boychuk is a freelance writer and columnist in Rialto, Calif. Feel free to e-mail him .]